Function readSimpleHuffmanCode

js/decode.ts:368–421

(alphabetSizeMax: number, alphabetSizeLimit: number, tableGroup: Int32Array, tableIdx: number, s: State)

  return 0;
}
function readSimpleHuffmanCode(alphabetSizeMax: number, alphabetSizeLimit: number, tableGroup: Int32Array, tableIdx: number, s: State): number {
  const codeLengths = new Int32Array(alphabetSizeLimit);
  const symbols = new Int32Array(4);
  const maxBits: number = 1 + log2floor(alphabetSizeMax - 1);
  const numSymbols: number = readFewBits(s, 2) + 1;
  for (let i = 0; i < numSymbols; ++i) {
    if (s.bitOffset >= 16) {
      s.accumulator32 = (s.shortBuffer[s.halfOffset++] << 16) | (s.accumulator32 >>> 16);
      s.bitOffset -= 16;
    }
    const symbol: number = readFewBits(s, maxBits);
    if (symbol >= alphabetSizeLimit) {
      return makeError(s, -15);
    }
    symbols[i] = symbol;
  }
  const result: number = checkDupes(s, symbols, numSymbols);
  if (result < 0) {
    return result;
  }
  let histogramId: number = numSymbols;
  if (numSymbols === 4) {
    histogramId += readFewBits(s, 1);
  }
  switch(histogramId) {
    case 1:
      codeLengths[symbols[0]] = 1;
      break;
    case 2:
      codeLengths[symbols[0]] = 1;
      codeLengths[symbols[1]] = 1;
      break;
    case 3:
      codeLengths[symbols[0]] = 1;
      codeLengths[symbols[1]] = 2;
      codeLengths[symbols[2]] = 2;
      break;
    case 4:
      codeLengths[symbols[0]] = 2;
      codeLengths[symbols[1]] = 2;
      codeLengths[symbols[2]] = 2;
      codeLengths[symbols[3]] = 2;
      break;
    case 5:
      codeLengths[symbols[0]] = 1;
      codeLengths[symbols[1]] = 2;
      codeLengths[symbols[2]] = 3;
      codeLengths[symbols[3]] = 3;
      break;
    default:
      break;
  }
  return buildHuffmanTable(tableGroup, tableIdx, 8, codeLengths, alphabetSizeLimit);
}
function readComplexHuffmanCode(alphabetSizeLimit: number, skip: number, tableGroup: Int32Array, tableIdx: number, s: State): number {
  const codeLengths = new Int32Array(alphabetSizeLimit);
  const codeLengthCodeLengths = new Int32Array(18);